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Hi All,
Well, the commuter has finally died so it's time for a replacement.
I'm currently riding an old Orange Evo2 frame adapted to city use but looking to replace this with either a Pompetamine or Roadrat with an alfine.
However, i'm struggling with the geometry calculations...
Pompetamine Geometry is as follows for a medium frame:
[IMG] 
[/IMG]
A Head Angle (°) 73
B Head Tube Length (mm) 104
C Effective Top Tube Horizontal (mm) 541
D Seat Angle (°) 73.5
E Seat Tube Length Centre to Top (mm) 510
F Chainstay Length (mm) 420
G Standover Height (in) 29.5
While the roadrat is as follows for a small long...
[IMG] 
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So, i'm comparing an effective top tube of 541 for the Pompetamine against 577 for the road rat however they appear to be calculated differently. The Pomp is measured to the vertical point above the centre of the seatpost clamp whereas the Roadrat is measured to where the horizontal would intersect the seat tube.
Any geometry experts want to work out what the top tubes would be if they were calculated the same way?
The Evo2 has a tt of 560 measured in the same way as the Roadrat and is pretty much spot on, I certainly wouldn't want to go shorter...
Alternatively, if you have any real world comparisons of the two having ridden them back to back your input would be appreciated...
Finally, if anyone has a Roadrat in small with an alfine 8 hub for sale let me know...
Thanks
Stan
They've both used the same calculation - as pictured on the Cotic. The Pompetamine is shorter because its designed for drop bars. (I thought the Roadrat was too, but it appears not with that length on a small.)
I think Pompetamines/Pompino's have the same geometry as the Kaffenback, which come up quite small for a given size, i have a large Planet X SL pro carbon and a large On one Scandal but had to get an extra large Kaffenback to get the required top tube length, speaking to one of the guys at PX and he said that they often have to size people up for them.
Maybe worth dropping them a line with the measurements of your previous bike and see what they suggest.
Hi Fellas,
Thanks for the input, I reckon giving On One a bell is probably a good shout.
Anyone ridden both bikes and able to comment?
Cheers
Road rat is 100% for flat bars an not drops
Thats why theu are different.
To get drops on my roadrat i have a 70mm stem !
I believe they used to make the Road Rat in long & short versions for flatbars & dropbars respectively but only make the long version now.